Background: The study aims were to model acute pain intensity and opioid consumption trajectories up to 72 hr after open hepatic resection, identify predictors of trajectory membership and examine the association between trajectory memberships and 6-month pain and psychological outcomes. This is a long-term analysis of a published randomized controlled trial on the impact of medial open transversus abdominis plane catheters on post-operative outcomes.
Methods: A total of 152 patients (89 males; mean age 63.0 [range: 54-72]) completed questionnaires on pain and related characteristics pre-operatively and 6 months post-operatively. Total opioid use was recorded several times over a 72-hr period while self-reported pain intensity scores were collected multiple times until hospital discharge. Analyses were carried out using growth mixture modelling, logistic regression and general linear models.
Results: Both pain intensity and opioid consumption showed that a four-trajectory model best fits the data. Patients in the lowest opioid consumption trajectory were more likely to be classified in the constant mild pain intensity trajectory. Age and baseline levels of anxiety significantly predicted opioid trajectory membership while baseline depressive symptoms significantly predicted pain intensity trajectory membership. Patients in the two highest opioid consumption trajectories reported significantly higher levels of pain catastrophizing at 6 months compared to patients in the other 3 trajectories (all p < 0.05).
Conclusion: High consumption of opioids after surgery is associated with higher levels of pain catastrophizing 6 months later. Identification of patients within these trajectories may lead to the development of early interventions targeted to high risk individuals.
Significance: Differences in initial levels of opioid consumption and rates of change in opioid consumption shortly after surgery can help predict long-term psychological responses to pain. Identifying key characteristics associated with initial opioid consumption can lead to the development of cost-effective early interventions targeted to high risk individuals.
Trial registration: ClinicalTrials.gov NCT01960049.
© 2018 European Pain Federation - EFIC®.